A fluorescence endoscope apparatus disclosed in Patent Citation 1 is known as an example of fluorescence observation apparatuses.
In endoscopic observation, observing an autofluorescence image is useful for diagnosing and observing a lesion because information of tissue different from that in a reflected image can be obtained. Observing autofluorescence, that is, tissue-derived fluorescence, has the advantage that the state of the lesion can be observed based on changes of the tissue.
To perform a diagnosis using autofluorescence, it is preferable to obtain fluorescence in a porphyrin-derived fluorescence region of 630 to 650 nm and fluorescence in a collagen-derived fluorescence region of 450 to 550 nm and to calculate and display the ratio thereof (for example, refer to Patent Citation 2).
Patent Citation 1: Japanese Unexamined Patent Application, Publication No. 2006-187598
Patent Citation 2: Japanese Unexamined Patent Application, Publication No. Hei 9-308604